Conveyor belt and method of making same

Abstract

A continuous conveyor belt of the type useful for transporting materials such as paper products from one location to another, and including a polyamide core and elastomerized top and bottom surface coatings on the core, is formed into a continuous band by a process which involves the use of a hot melt foil sheet placed between the ends of the belt. The foil sheet includes a polymer material which softens under heat and pressure, and which solidifies when cooled to bond together the ends of the belt. Typically each end of the belt is feathered, and the ends are juxtaposed in an overlapping relationship with the foil sheet therebetween. Temperatures of 325°-425° F. (163°-218° C.) are typically used to soften the adhesive.

What is claimed is: 
     
       1. In a continuous conveyor belt having a longitudinal axis and comprising an elongated tape with a first end and a second end spliced together, said tape comprising a polyamide core and an elastomerized surface coating on said core, the improvement wherein each end of the belt is feathered at a non-perpendicular angle relative to the longitudinal axis of said belt to provide opposed feathered surfaces in overlapping relationship with no overall increase in the thickness of the belt, said feathered surfaces being bonded together with a hot melt foil adhesive. 
     
     
       2. A belt according to claim 1 wherein the hot melt foil adhesive having a thickness in the range between about 0.2 and about 0.6 millimeters is employed to bond together the surfaces. 
     
     
       3. The belt according to claim 1 wherein the polyamide core is selected from the group comprising the condensation product of adipic acid and hexamethylenediamine, and polymerized caprolactum. 
     
     
       4. In a conveyor belt having a longitudinal axis and comprising an elongated continuous strip having a first end and a second end and a splice between said ends, said belt comprising a core of a polyamide material and a surface coating comprising an elastomeric material providing a friction surface for objects placed on the belt, the improvement wherein said first end and said second end are tapered and have an angle relative to said longitudinal axis such that the sum of the two angles is about 180 degrees, said splice including the two tapered ends of the belt in overlapping relationship with one another with no overall increases in the thickness of the belt and a bonding agent comprising a thin flexible foil of hot melt adhesive between and bonding said tapered ends together. 
     
     
       5. The conveyor belt according to claim 4, wherein each of the two tapered ends 180 angles, one of said angles between about 0 and about 30 lie in a plane inclined laterally and longitudinally with respect to the longitudinal axis of the belt. 
     
     
       6. The conveyor belt according to claim 5 wherein the splice is subjected to heat and pressure to soften the foil and is then cooled to solidify the bond. 
     
     
       7. The conveyor belt according to claim 6 wherein the splice is heated to a temperature between about 325° F. (162° C.) and about 425° F. (218° C.). 
     
     
       8. In a method of joining two ends of an elongated belt having a thickness and a longitudinal axis and comprised of a core of a polyamide material, and a cover layer on the surfaces of said material, said cover layer providing a non-slip surface, the improvement comprising: providing a thin foil of a hot melt adhesive between the ends of the belt, tapering said ends at a non-perpendicular angle relative to the longitudinal axis of said belt, positioning the tapered ends of the belt with the foil therebetween with no overall increase in the thickness of said belt, subjecting the ends of the belt and the foil to heat until said foil is softened, and thereafter cooling the foil and ends to solidify said adhesive whereby the ends are bonded together. 
     
     
       9. The method according to claim 8 wherein the foil sheet before heating has a thickness in the range of between about 0.2 and about 0.6 millimeters. 
     
     
       10. The method according to claim 9, wherein the ends are overlapped with the foil therebetween to form a splice having the same thickness as the belt, and tapering said ends for said splice to lie in a plane inclined both laterally and longitudinally with respect to said axis. 
     
     
       11. The method according to claim 9 wherein the heating of the ends is carried out at a temperature between about 325°-425° F. (163° C. and 218° C.). 
     
     
       12. The method according to claim 11, wherein the heated is heated to a temperature of about 375° F. (192° C.) for a period of time equal to about 2 minutes per inch of belt width. 
     
     
       13. The method of joining two ends of a belt with essentially no overall increase in the thickness of the belt, said belt comprising a core of polymer material and a cover layer on the surface of said polymer material, said cover layer providing a non-slip surface, said method comprising the steps of: a) cutting said belt to a desired length and width, said belt having two ends and a longitudinal axis;   b) tapering the two ends of said belt for each belt end to have a tapered surface in a plane inclined both laterally and longitudinally relative to said longitudinal axis;   c) applying a foil sheet of hot melt adhesive on one of said tapered surfaces;   d) overlying the other of said tapered surfaces on said foil such that said two ends are in an overlapping relationship with said foil disposed between said two tapered surfaces; and   e) applying heat to said cover layer of said belt until said foil melts and adheres together said tapered surfaces.   
     
     
       14. The method as defined in claim 13, wherein said plane of said tapered surface is laterally inclined about 30 degrees relative to said longitudinal axis. 
     
     
       15. The method as defined in claim 13, wherein said core includes a polyamide material. 
     
     
       16. The method as defined in claim 15, wherein said polyamide material is selected from the group comprising the condensation product of adipic acid and hexamethylenediamine, and polymerized caprolactum. 
     
     
       17. The method as defined in claim 13, wherein said cover layer includes a material selected from the group consisting of natural rubber, butyl rubber, neoprene, styrene-butadiene rubber, polyvinyl chloride, ethylene-propylene rubber, polyesters, polyurethane, and mixtures thereof. 
     
     
       18. The method as defined in claim 13, including the step of cutting said foil to the width of said belt and to the length of said tapered surfaces. 
     
     
       19. The method as defined in claim 13, including the step of applied pressure to said cover layer as said heat is applying to said cover layer. 
     
     
       20. The method according to claim 13, wherein the foil sheet before heating has a thickness in the range of between about 0.2 and about 0.6 millimeters. 
     
     
       21. The method according to claim 13, wherein the heating of the cover layer is carried out at a temperature between about 325°-425° F. (163° C. and 218° C.). 
     
     
       22. The method according to claim 21, wherein the cover layer is heated to a temperature of about 375° F. (192° C.) for a period of time equal to about 2 minutes per inch of belt width. 
     
     
       23. An endless conveyor belt comprising an elongate strip of belt material having longitudinally opposite ends, laterally opposite side edges, top and bottom surfaces and a splice between said ends, said belt material comprising a polyamide core and a surface coating of elastomeric material, and said splice comprising laterally and longitudinally overlapping tapered surfaces on said opposite ends and a foil of hot melt adhesive between and bonding said tapered surfaces together, each of said tapered surfaces lying in a plane which is inclined relative to said top and bottom surfaces and relative to said opposite side edges.